Posted
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Unknown Lameron Wednesday July 06, 2011 @01:10PM
from the beach-photos-with-a-zeta-reticulan dept.

coondoggie writes with an article in Network World. From the article: "The European Space Agency says it has completed what it calls the largest digital camera ever built for a space mission — a one billion pixel array camera that will help create a three-dimensional picture of the Milky Way Galaxy. Set to be launched onboard the ESA's galaxy-mapping Gaia mission in 2013, the digital camera was 'mosaicked together from 106 separate electronic detectors.' ESA says that Gaia's measurements will be so accurate that, if it were on Earth, it could measure the thumbnails of a person on the Moon."

This telescope can directly image objects 1000 km across at the center of the galaxy.

Well, maybe, but that's assuming said object is really luminous. Sure, you can get 1000km resolution on a star, but it does you no good to have 1000km resolution on an exoplanet if the number of photons reaching you from the exoplanet are less than your noise floor. I could be wrong, but I don't think this resolution is *quite* as exciting as it sounds... unless of course you attach it to some wide aperture high quality optics.

Remember, photons are photons whether they are reflected or traveling directly from a light source. There is no implication of their source. If you designed a satellite to observe celestial bodies, would you build it so it could observe sources and reflecting bodies? I would.

Spatial resolution is spatial resolution no matter what units you're using. You've still got to translate pixels to microarcseconds somehow - I'm sure that stellar parallax must still be derived from multiple measurements over time, whi

That can't be right, surely. I mean, I'd expect such a camera to come across some sort of mega engineering projects if that were the case, and directly image many planets, which I thought was many years down the line? Or is it set up just for stellar observation with limitations that preclude what I'd just said?

And as to why we were able to get to the moon, but can't now, remember that in the 60's in the middle of Vietnam, NASA had more funding than the DoD. Now NASA's budget is less than the cost of air conditioning for the DoD. And people still bitch and moan about how much NASA is spending.

Nope, that's worthless. We should have taken from the small subset of the federal budget that is NASA, and given to the larger subset of the budget which is education, while ignoring the vast bottomless pits that money is thrown towards now.

Education isn't purely funded by the federal government either. Schools have the luxury of being funded by states and local government also.

Yup. There was someone ranting one day about how much NASA spends, so I took the time to go through the federal budget numbers, break it down, put it back together, and showed how insignificant the NASA budget was compared to other things that we really don't need and shouldn't be doing.

Consider how much money has been put into new fighter aircraft, when there isn't an enemy with the capability of deploying aircraft to even get to CONUS. Some of the projects are dropped afte

Turn off your computer now. Also turn off your electricity and water, stop eating any foodstuffs not hunted (by hand) or gathered in the wild, take off any clothes you're wearing that aren't made from animal hides or woven grass, and go chip some tools out of flint. Actually, scratch that last part -- who needs to waste time on researching how to break perfectly good rocks when you can just pick them up and throw them at things? Be careful, though; you don't want the fire in your cave to go out, since it

computers existed before NASA by a number of yearsfoodstuffs not gathered in the wild is cultivation, and there are plenty of people who might lay claim to that before NASAThe Greeks had woven fabric, synthetic development was during WWII for military reasonsWhen you throw rocks at bigger rocks you break them, it might help your grasp on realityand that fire bit is amusing considering a lot of people tend fires in their lives daily, whether its a pilot light for the furnace or a fire out side of a tent

In your case, what you're missing is the point, by a mile. This isn't about NASA. It's about the overall value of research, without which we would all still be living in caves and scratching bare-handed in the dirt. If you don't accept that, that's your privilege, but you should have the courage to act on your beliefs, which means GTFO of the modern world.

Realistically, other than the silliness of it (and the atmospheric distortion), the camera only has a billion pixels (and really great optics). If they're trying to focus in really great detail, they can't cover that many people or that much area at once. 1000 people would be a megapixel each (so wear your hats, folks), but if you were building a spy satellite instead of one intended for deep astronomy pixels, you could probably do

To avoid any confusion, we have finished the assembly of the focal plane assembly (i.e. those 106 large CCDs), but not the full-up satellite itself. That still has a way to go, with launch likely at the end of 2012 or early 2013. But it's nevertheless a great achievement to have the huge detector array done and is a real milestone for us.

Also, Gaia isn't taking pretty pictures of the sky per se: via repeated scans over the sky, it's going to provide extremely accurate positions and velocities for about one billion stars in the Milky Way, allowing us to trace their motions back (and forward) in time, and thus understand how the Milky Way was put together in the first place. It does much, much more than that, so if you're interested, I suggest you follow the link in the original submission for more.

Not really; these are very specialised custom CCDs made for Gaia alone, to its specific requirements. Because of this, they're a very long lead item and need to be tested rigorously, which means that they needed to be done early. That said, most of the parts of Gaia are ready by now, and the remaining time before launch will be needed for integration and testing of the whole system.

While you're right about the rapid pace of detector development in the commercial sector, those are very different beasts t

By the scale of the upcoming James Web Space Telescope or even by the Hubble Space Telescope, GAIA has some pretty small primary mirrors (1.45m). Hell, there are probably some amateurs with telescopes with bigger mirrors than that (though not 1.5 million kilometers in space!). I'm amazed that with such small mirrors it will have the sensitivity to do all that is claimed it will like find (hopefully) tens of thousands of brown dwarfs which are very dim (hence the name). (Of course ACCURACY not sensitivity is the main goal of this thing, that's why even though it could have the resolution to pinpoint a thumbnail on the moon it couldn't see it unless it was a very bright thumb!)

Still I am not a professional astronomer and since this is being done by the same(?) people as who created hipparcus, the previous spacecraft of this type, I'm optimistic that it will be equally successful. Someday we can hope here will be a version of this with really big mirrors, maybe that will allow us to get the remaining 99% of the galaxy. Still to think that soon we may have a pretty good 3D model of the galaxy (with a billion 3D data points) is amazing considering that the only comparable example of this was in Star Trek Voyager's "Map Room" set several centuries in the future! And they were still lost!

If one of the goals of astronomy is to show humanity's place in the universe, I think this goes a long way to fulfilling it. I really really want the 3D dataset when it comes out after 2018 so I can take my own virtual voyages through the milky way!

There's some confusion here. The raw image resolution provided by Gaia's mirrors is one thing and your estimate of 0.08 arcsec may be appropriate there.

On the other hand, Gaia's real job is to measure the position of stars very accurately, and that it can do down to a few microarcseconds: it doesn't resolve the stars, of course, but provides extremely accurate positions for them. By doing this repeatedly over several years, it can then see objects move by very small distances.